Apparatus for drilling diamonds and like purposes



C. G. EDEN I July 13, 1943.

APPARATUS FOR DRILLING DIAMONDS AND LIKE PURPOSES Filed March 12, 1942Inven'tor: Christophev G. Eden,

His A'btovneg Patented July 13, 1943 APPARATUS FOR DRILLING DIAMONDS ANDLIKE PURPOSES Christopher G. Eden, Rickmansworth, England,

assignor to General Electric Company, a corporation of New YorkApplication March 12; 1942, Serial No. 434,446 In Great Britain March19, 1941 4 Claims.

diamond have to be separated from each other at intervals (generallyconsiderably less than one second) in order that the diamond dust andoil with which the drill is supplied may reach the bottom of the hole;the required separation is usually less than 1 mm. and often less than0.1 m. I

For the most satisfactory results the following conditions have to befulfilled: (1) the extent of the separation is independent of the depthof the hole already drilled; (2) the separated parts, when they meetafter separation, do so without excessive impact; (3) the ratio of theperiod of separation to the period of contact is readily variable; (4)the pressure of the drill on the diamond during drilling is constant.

An object of the invention is to provide simple means for attaining, orat least approaching very nearly, all of the said conditions. A machinefor a purpose like diamond drilling means one in which the periodicseparationof two parts by a distance less than 1 mm. and with a periodless than 1 sec. has to be effected subject to conditions closelysimilar to those aforesaid.

In what follows it will be assumed for brevity that the bearings of therotating drill are fixed and that the diamond carrier is moved by adriving member whose motion is completely determinate. It ispermissible, though generally less desirable, to make any modificationthat leaves the relative motion of diamond and drill or tool unaltered;e. g., to fix the diamond carrier and move the drill. Any statementindicating the scope of the invention must be interpreted so as to admitof such modification.

According to the invention this object is achieved preferably byconnecting the diamond carrier to the driver member through a hydrauliclink and providing means whereby, during one part of the cycle, aconnection is made between the fluid in the hydraulic link and areservoir of fluid, so that, during this period, the drill and diamondcome into contact whatever the position of the driving member.

The invention will now be explained further with reference to anembodiment, described by way of example and illustrated in theaccompanying drawing by a partly sectional diagrammatic elevation.

Referring to the drawing, l is the diamond carrier or holder resting asusual on rollers 2, of

against the end of a horizontally disposed needle or drill (not shown).The hydraulic link consists of a. vessel 3 filled with liquid (usuallyoil) into which enter the pistons 4, 5. The outer end of piston 4, whichis the driven member, is connected to the diamond carrier by a link 6,so that the motion of the carrier I in a horizontal direction is alwaysthe same as that of the piston 4.- Piston 5, which is the said drivingmember, is forced to enter and leave the cylinder by means of thestraight cam I2 against which its outer end is pressed by the spring I.The cross section of the piston 4 is preferably (as shown) greater thanthat of the piston 5; but of course this is not necessary if the motionof 5 can be controlled suificiently finely.

If the vessel 3 were always closed during operation, the oscillations ofthe piston 5 would be reproduced in the motion of piston 4 (andthereforeof the carrier), on a scale reduced by the ratio of the crosssection of piston 5 to that of piston 4. The carrier would oscillatebetween two fixed positions; once the drill had ceased to press on thediamond when the carrier was in its forward position, owing to the wearon either or both, drilling would cease. (Usually, of course, the drillwears much more rapidly than the diamond.)

In order that pressure between the drill and the diamond may bemaintained, connection is made between the liquid in the vessel 3 andthat in a constant-pressure reservoir 8 during (and only during) theperiod when the carrier is in its forward position and the drivingmember is at rest. The diamond is thus pressed against the drill duringthis period by a constant force; but since the connection to thereservoir is broken before the driving member moves, the excursion ofthe carrier produced by the driver does not depend on the position thatthe carrier takes up under the constant pressure.

The periodic making and breaking of the said connection is effected bycausing the shaft 9 driving the cam to act as a tap in the tube I0,connecting the vessel 3 to the reservoir 8 in a. manner sufficientlyindicated in the drawing.

In order that the part of the cycle during which the diamond and drillare separated may be readily varied, a link II' of easily variablelength .s inserted in the connection between the cam l2 and the crankpin I3 driven by the shaft 9. Thus the link may consist in well-knownmanner of a sleeve l4 into which rods l5, l6, being screw-threads ofopposite senses, work at which only the hindermost is shown, and pressedeither end. It is thus possible to secure that the cam follower l1 movesbetween the points l8, [9 on the cam or between the points 20, 2| orover any intermediate range. In the first alternative, the period ofseparation is only that when the carrier is moving; in the second, theperiod of separation is substantially the whole cycle; in the third itmay be anything between these extremes.

The velocity with which the carrier approaches the drill in its forwardposition may be made very small by shaping the cam surface suitably. Allpossibility of impact under the influence of the driving member may bethus avoided. Objectionable impact under the constant pressure inreservoir 8 is highly improbable, since the amplitude of the motionunder this pressure will always be very small. Roughly speaking, itcannot be greater than the amount by which the depth of the hole wasincreased during the drilling period preceding the last separation. Butimpact can always be avoided by providing sufllcient resistance to theflow of liquid between the reservoir 8 and the vessel 3.

In an alternative embodiment the piston 4 itself is used as thediamondcarrier, the diamond being mounted on the outer end of it.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In apparatus of the class described, the com-' bination of a drivenmember, driver mechanism for urging said driven member forward in agiven direction and periodically retracting it a short distance, andhydraulic link mechanism connecting said driven member to said driver'mechanism and providing means for periodically supplying a constantpressure to the fluid in said link mechanism only when the driven memberis in its forward position and the said driver mechanism is at rest sothat the driven member is then urged forward by a force determined bythe said constant pressure means.

2. In apparatus for drilling diamonds and like purposes, the combinationof a work holder, driver mechanism for urging said work holder forwardin a given direction against a drill and periodically retracting it adefinite short distance which is independent of the depth of the holealready drilled, and means, independent of said driver mechanism, forperiodically applying a deflnite constant force to said work holder onlyduring the period it is in its forward position and the said drivermechanism is at rest so that the work holder contacts the drill with adefinite pressure regardless of the position of the driver mechanism.

3. In apparatus of the class described, the combination of a drivenmember, driver mechanism for urging said driven member forward in agiven direction and periodically retracting it a definite shortdistance, hydraulic link mechanism connecting said driven member to saiddriver mechanism, a constant-pressure fluid reservoir, and means forperiodically connecting the fluid in said link mechanism with saidreservoir only durng the period when said driven member is in itsforward position and the said driver mechanism is at rest so that thesaid driven member is urged forward during the said period by a forcedetermined by the pressure in said reservoir.

4. In apparatus of the class described, the combination of a drivenmember, a driving member, a hydraulic link connecting said driven anddriving members, cam means engaging said driving member to urge saiddriven member forward, through said hydraulic link, and to retract it adefinite short distance, a constant-pressure fluid reservoir, a conduitconnecting said reservoir with the fluid in said hydraulic link, valvemeans forming part of said conduit, said valve means being connected tosaid cam means, and said valve means and cam means being so constructedand arranged that the valve means periodically connects the fluid insaid link with said reservoir only during the period when said drivenmember is in its forward position and the driving member is at rest sothat the said driven member is urged forward during this period by aforce determined by the pressure in said reservoir.

- CHRISTOPHER G. EDEN.

